Iguanura exilis Henderson, 2025

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 157

10. Iguanura exilis Henderson , sp. nov. Type:— INDONESIA. Central Kalimantan, upper Katingan river, c. 50–100 km WNW of Tumbang Samba, Tumbang Merak, c. 1°15’S 112°40’E, 200 m, 20 November 1982, J. Mogea 3462 (holotype BO n.v., BO image!, isotype L-0616425!). Plate 4.

Stems 1.0 m long, 0.8(0.6–1.0) cm diameter, solitary. Leaf sheaths 9.0 cm long, tubular, mostly closed opposite the petiole, cleanly falling, covered with a thin layer of indumentum; ocreas well-developed, separating early into fibers and disintegrating; petioles 9.6 cm long; rachises 21.8(18.0–28.5) cm long; leaf blades undivided or divided, not rounded at the apex, with a deep split; leaf veins parallel; adaxial leaf veins prominent, rectangular in cross-section; pinnae 2(1–4) per side of rachis. Inflorescences spicate; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles length not recorded, not wooly tomentose; rachises 0.0 cm long; rachillae 1, 22.8(22.5–23.0) cm long, 1.6(1.5–1.8) mm diameter, proximal part of rachilla with markedly distantly spaced triads, glabrous or sparsely to densely tomentose, not filiform with triads sunken in shallow, more or less closely spaced pits; rachilla bracts not elongate; distal triad bracteoles well-developed; distal part of flower pits glabrous; staminate flowers 2.0– 2.5 mm long with blunt apices; anther margins not recorded; fruits 9.1 mm long, 4.8 mm diameter, ellipsoid, ridged, the surfaces drying pebbled, pink, red, or bright red; endocarp polygonal in cross-section; endosperm not recorded.

Distribution and habitat:— Indonesia (West Kalimantan) in primary Dipterocarp forest at 390(150–1,200) m elevation ( Fig. 9 ).

Taxonomic notes:— Iguanura exilis is recognized as a phylogenetic species — see notes under I. macrostachya . It is characterized by its tubular leaf sheaths that are mostly closed opposite the petiole, proximal part of the rachilla with markedly distantly spaced triads, fruit surfaces drying pebbled, and endocarps polygonal in cross-section.

One specimen (J. Mogea 3834) comes from an unusually high elevation, 1,200 m.

Figures

FIGURE 9. Distribution of Iguanura elegans, I. exilis, I. grandis, and I. lunata.